The Effects Of Long Term High Voltage Electrostatic Fields Stress On The Feeding Behavior And Physiological And Biochemical Characteristics Of The Sitobion Avenae (Fabricius)

The earth,as a negative electric body,forms an atmospheric electrostatic field in which the organisms on the earth lived for many years.There are certain charged substances in the living body that are closely related to their growth and development.However,in recent years,the construction of a series of large-scale electric power projects,such as High-voltage DC transmission lines,has been increasing,leading to changes in the natural electric field environment.And such high-voltage facilities are generally built in farm and other open fields.Consequently,the kinds of biological effects on animals and plants that can be caused by High-voltage electrostatic fields（HVEF）has attracted researchers’attention.At present,research in the field of agriculture shows that HVEF has positive or negative biological effects on organisms,but because of complex physiological and metabolic mechanisms exist in animals and plants,its specific mechanism is still unclear.In addition,previous studies on HVEF are concentrated in the aspects of medicine and plant seed germination.There are few studies on insect and the interaction between insects and plants under stress,and there is a lack of studies on insect genetic variation and coping with stress under long-term environmental stress.Sitobion avenae（Fabricius）,as an R-strategist,is not only an important pest on wheat,but also has the characteristics of small body sizes,high reproduction rate and short generation times.Thus when the external conditions change,they can respond with rapidly to cope with environmental stress.These characteristics further testify S.avenae are ideal experimental materials for studying ecological stress.It can be seen that this research not only has important theoretical significance,but also has important practical value.Based on the above scientific problems,based on the previous research of our team,in order to imitate the natural HVEF stress,wheat seeds and S.avenae nymphs（born within 12h）were exposed to an HVEF of 4 KV/cm for 20min and at 5 KV/cm intensity for 40min,respectively.Controls received no treatment（0 KV/cm）.All treatment combinations（4 KV/cm-20 min,5 KV/cm-40 min）were processed through 40 generations.Feeding behavior of the 5th,10th,15th,20th,27th,33th and 39th generation aphids was monitored using electrical penetration graph（EPG）technology,and the mean relative growth rate（MRGR）was also measured in those same generations.In order to further explore the expression profiles of antioxidant enzymes（CuZnSOD,MnSOD,CAT and POD）gene in S.avenae in response to stress under the long-term exposure on HVEF at the level of molecular.Partial of CuZnSOD and MnSOD genes cDNA sequence were firstly cloned by RT-PCR.And gene expression levels of S.avenae were measured by qRT-PCR of 4th,11th,21th,33th,40th generation.Which may be could provide a basis for the research on biological genetic evolution and ecological regulation of aphids.The result shows that:1.Research on the weight increase of S.avenae indicated that weight initially increased and was then inhibited in later generations of the aphid after treated by HVEF.Growth promotion was mainly manifested in the weight difference and the MRGR of S.avenae being higher than the control group during 10th-33th generations in the HVEF treatment group with the differences being significant in 15th,20th and 33th generation.However,the weight gain of S.avenae is suppressed when continued to be electrostatically irradiated by HVEF to the39th generation,especially at the treatment intensity of 4 KV/cm-20 min.Which indicated that HVEF was contributes to the growth of S.avenae within a certain generation（eg,10th-33th generation）,but it will not be conducive to the growth of S.avenae beyond a certain period（after 33th generations）.2.Through the analysis of the feeding behavior parameters of many generations of S.avenae,the results indicate that the non-probing time was shortened when S.avenaewas exposed to HVEF until the 10th-15th generations.However,the total durationof non-probingbegan to increase in later generations.This also demonstrated that short-term electrostatic treatment on S.avenae has a promoting effect for feeding behavior,but the promotion effect gradually disappears with the prolongation of treatment time.This is consistent with weight change as generations increase.In addition,feeding behavior of S.avenae in the phloem also showed that as generations increased,number of probings in the phloem by S.avenae was first increased and then decreased with the prolongation of generations exposed to HVEF.This was especially significant at the 4 KV/cm-20 min treatment intensity.3.Antioxidant enzyme genes showed up-regulation patterns aftershort-term high-voltage electrostatic stress（shown in the 4th generation）.With the prolongation of stress time,the expression of four antioxidant enzyme genes began to decrease after the 4th generation.The expression levels of two kinds of SOD genes were significantly increased when the high-voltage electrostatic treatment was continued for 40th generation.Under the same generation,the expression level of POD gene was also significantly up-regulated in the treatment group,further illustrating the mutual coordination of the two antioxidant enzymes.Meanwhile,elevated expression of the POD gene further compensates for the ability of H₂0₂ to be cleared by inhibition of CAT gene expression.4.In summary,the comparison of the two treatment intensities showed that the high-voltage electrostatic treatment at the intensity of 4 KV/cm-20 min has a greater influence on the probing numbers of S.avenae,and the effect is more significant.Moreover,the result demonstrated that the expression of antioxidant enzyme genes of S.avenae were significantly affected by HVEF and generational changes under 5KV/cm-40min treatment intensities,of which has the strongest scavenging ability of superoxide radicals.